Industrial processing and manufacturing applications, such as semiconductor manufacturing, typically require the safe handling of toxic, corrosive and/or flammable hydridic and halidic gases and mixtures thereof. By way of example, the semiconductor industry often relies on the gaseous hydrides of silane (SiH4), and liquefied compressed gases such as arsine (AsH3) and phosphine (PH3) for wafer processing. Various semiconductor processes utilize SiH4, AsH3 or PH3 from vessels that have storage pressures as high as 1500 psig. As a result of their extreme toxicity and/or pyrophoricity and high vapor pressure, uncontrolled release of these gases, which can occur due to delivery system component failure, or human error during cylinder change-out procedures, may lead to catastrophic results. For example, the release of a flammable gas such as silane may result in a fire, system damage and/or potential for personal injury. Leaks of a highly toxic gas, such as arsine, could result in personal injury or even death.
A pyrophoric gas such as silane after filling into a package, is attached with an outlet cap. However, internal leakage of silane across the valve seat can accumulate within a dead space volume behind the outlet cap. When the cap is removed, the leaked silane can emerge from the user port and come into contact with air, resulting in a “popping” sound. The popping sound can be accompanied by a flame in the user port. Relatively smaller silane leaks may give no visual indication of a leak, but yet can result in a popping sound when the silane comes into contact with air. The popping can also be accompanied by a flame in the user port.
The internal leakage of silane across the valve seat can occur during the transport of silane cylinders, during which sufficient momentum can be imparted to the valve seat causing it to momentarily open and then reseat. This momentary opening of the valve seat is known as “burping” in the industry, and can put sufficient pressure under the outlet cap, such that popping can occur when the cap is removed. Burping can be a particular problem with spring-loaded pneumatic valves.
Additionally, silane can oxidize to form silicon dioxide white particulates, which can then deposit on the valve seat. By virtue of the deposited particles, the valve can no longer make a leak-tight seal when the valve is closed, thereby resulting in leakage across the port (known as cross porting in the gas industry).
There is an unmet need to improve the safety of silane packages. Other aspects of the present invention will become apparent to one of ordinary skill in the art upon review of the specification, drawings, and claims appended hereto.